A phrasal verb is a combination of a simple common verb such as turn or put with one or more prepositions such as up or out. So we have the phrasal verbs:
turn out - turn up
put out - put up
Learners find phrasal verbs difficult because they hear/see a string of words they know but which do not produce a comprehensible message:
It turned out that no-one turned up.
I'm put out you can't put me up.
There are no useful rules for learning the meanings of phrasal verbs from their constituent parts, so each one has to be learned as a separate entity. Unfortunately for ESL students everyday English is absolutely teeming with phrasal verbs.